Armored conductor.



Patented Nov. 20, 1917 2 SHEETS-SHEET! C. P. MADSEN.

ARMORED CONDUCTOR.

APPLICATION FILED SEPT. 6. 1913.

C.P.MADSEN.`

ARMORED CONDUCTOR.

APPLICATION FILED SEPT. 6. |913.

Patented Nov. 20, 1917k 2 SHEETS-SHEET 2.

CHARLES PflVIADSEN, @F CHICAGQILLINGIS.

Ammann cometieron.

To all whom t may concern.'

Be it known that I, CHARLES P. MADSEN, a citizen of the United States of America. and a resident of Chicago, county of Cook, and State 'of Illinois, have invented certain new and useful Improvements in- Armored Conductors, of Which the following yis a specification.

The main objectsv of this invention are to provide an improved form of armored conductor adapted for high temperature eleotric heater service, and especially such a conductor adapted to withstand beingheated to incandescence and formed to concentrate the delivery of heat; and to provide improved method and means for forming and lacino such an armor u on the insulatedv P e conductor in the manner specified.

@ne of the chief difficulties in constructing many types of electrically heated apparatus lies in protecting durably the heatgenerating conductor. This difficulty is especially met with in hightemperature apparatus in which the heat is transferred from the generating conductor to the Work body by radiation or by air convection, as for instance in toasters, broilers, and air heaters. rIhe seriousness of this dificulty is apparent in view' of certain conductors now used for heat generating purposes `which, even-"in open air, can -be maintained Without injury at a temperature much higher than required for'the service performed, but whichv fail when embodied in the types of apparatus commonly in use,with the result that such devices are short lived.

Research and experiment show that the termination of usefulness in the type of apv paratus referred to is nearly always caused either by changes due to exposure to the air, or by exterior electrical or mechanical injury to the conductor. .The conductors in such apparatus must almost of necessity be thenfmechanically Weakest part of the apparatus, and are therefore peculiarly liable to injury by handling, which the balance of the apparatus -Withstands Moreover, in a high temperature appara-l .tusthe conductors are in a condition which renders them abnormally sensitive and susceptible to injury. The heat generation conductors are of high specific resistance, and

operate at a high current density.y The voltage drop per unit of length is relatively great, and therefore short circuiting or shunting of a portion ofv theconductor, as

Specification of Letters Patent.

alone possess for instance a single turn, cau-ses an abnormally heavy current to pass which injures such conductor at the points of contact. Furthermore, experience has shown that the Patented Nov. 2d, i931?.

Application filed September 6, 1913. Serial No. 788,437.

high heat emissivity rate vand the molecular disturbance under which conductors operate, cause the injury to be greater than Would otherwise be the case. Thus the edect Iof a partial short circuit or shunt is likely to be a complete severing ofh the conductor rather than a mere pitting of the surface.

So great have been these ditiiculties and so little have they been understood that they have largely prevented high temperature air convection and radiation methods .from

being extendedwhere such methodsnvvould really be most effective.

Attempts have been made to overcome these difficulties by protecting the heat conductor in various Ways. No insulating materials or compounds are available Which the required properties. ThereforeVattempts have been made to armor the conductors With sheet metal applied mechanically with an insulating inedium interposed, butl incandencence cannot be maintained with such an armor. i'

It \is difficult in practice to manufacture suchan armor which will maintain its shape and remain in solid lrelation with its con- .tained conductor under the conditions of f.'

continual contraction and expansion met with in practice. The resultant looseness in vtime interposes av considerable temperature.- lag in the thermal path, thereby reducing' both efficiency and speed and` also shortening the life of the heat generating conductor by requiring a higher generating rate. Furthermore, such armors are necessarily of considerable mass, which interposes a further resistance and lag in the thermal path.

By this invention I overcome these dithculties by electrically depositing a thin shell of highly refractory metal directly upon and in close contact with a suitably insulated conductor. I find that this method possesses many advantages, some of Which are: that an armor of this character is extremely adherent, formingV a much more intimate and permanent Contact with the insulated conductor than can be obtained by mechanical means; that the shell can be made very much thinner than is possible in a mechanically placed armor; that it is possible to armor much smaller sized heating elements, or groups of conductors, or individual conductors of much smaller size than is possible where the conductor is armored by mechanical means; and that metals, alloys, or com- .binations of metals can be thus deposited which are more refractory and betteradapted for the purpose than any metal obtain- A able by mechanical processes.

lIt ispossible to apply this invention in several ways, and I do not wish this invention to bey construed as limited to any spe'- cific application. To form a heating element a conductor is formed into a unit of any geometric shape desired. Itis then sulated in any suitable manner, as for 1nw thin electrical deposit of refractory .metal stance with thin porcelain enamel, and a is then formed thereon. n

The electrlc deposit may be disposed to armor a heating unit as a whole, or it may be arranged to inclose only individual limbs c or-members of a unit. Furthermore an eX- tended utility may be obtained by depositing the armoring shell of metal to inclose a metallic or non-metallic supporting member or frame work together withv an insulated conductor mounted thereomin which `casegthe armor serves as a mechanical fastening or binder between the'conductor and its supporting frame work, as well as a protection for the conductor. p f .This process may also be utlhaed forother purposes than protecting formed heating units. -It may for instance be used in the electric heating art for coating or armorlnga continuous insulated conductor of indefinite length." Such a conductor is more convenient for forming a radiant type of heating unlt-of 'large size or a unit in which the 'conductor- 'elements are widely spaced. Such a conducto'r may be made by passing the insulated wire to be armored through a continuously operating plating bath and moving the wire at a definite rate adapted to thickness of deposit.

Two or more parallel wires insulated from each other in a common mass ofv insulation may be covered by a single deposited metal armor. y

I do not wish this ,invention t0 be understood as being limited to'a particularmetal used in making the armor, nor to a specific process used. I have found, however, that a coating of nickel, or a combination of algive the proper `loy of nickel and another metal-,' for eX-' ample vanadium,'are suitablef v In carrying out. the process Iprefer to use as an insulation a coatin of' porcelain enamel, fused silica, or a special glass. The outer surface. of thisl insulation is rendered conductive in any suitable way, as for example by applying an -adhesive coating and dusting it with a metal powder or n lumbago,

. or by painting it with an aluminum or bronze paint. The unit so treated is then ready for the plating bath.

' types of construction it is possible to attain a much higher temperature or intensity than is possible inI inclosed types, and the speed of operation and efficiency are greater. An

y illustration of the utilization of this` principle is given in one of the drawings hereinafter described, which shows a volute heat generating conductor of only a few square inches of incandescent surface capable of doing more work per unit of power input than would be performed by a 6 inch solid disk stove having a surface of about 30 square inches, because with the same power consumptlon the heat intensity in the former is very much higher, and the efiiciency is correspondingly greater.

i Severalillustrative embodiments of this invention are shown in the accompanying drawings rin which- Figure 1 isa plan view of a heater elementcomprising a metallic supporting plateY enameled on one side, and having a resistance conductor imbedded in and insulated by the enamel, and an outer shelly or armor `Ielectrically deposited upon the enamel.

Fig. 2 isa section along the line A-A of Fig. 1. Y l

Fig. 3 is across section of a modified form of heater element in which the conductor is woundvabout the ,supporting plate instead of vdisposed upon one side only, and in which the deposited armor completely envelops the element.

Fig. 4 shows a section .of armored wire `.having a thin insulation disposed between the wire and a Athin electrically deposited metalvcovering.

Fig. l'shows a section of armored twin conductor oir twistedpair of wires embedded in insulation and protected by a single shell of deppsitedarmor. I

Fig. 6 is a plan View of a heater `unit comprising an insulated heat generating conductor arranged in the form' of a volute spiral supported yon a skeleton frame made up of radiating `arms one-half of the view 'showing the parts before the armor is deposited thereon and the other half illustrating the completed unit.

Fig. 7 is a vertical cross section along the line A--A of Fig. 6.

`Fig. 8 is an enlarged sectional View on the line A--A of Fig. 6.

In the construction shown in Figs. 1 and infinitas 2 there is provided a supporting plate or backing member 1 having a coating o t suitable insulation 2 on one side, as for instance enamel, and a heat generating resistance member 3 embedded Within said insulating material, and a thin outer protective shell or armor lconsisting olE suitable refractory metal electro-deposited upon the insulation as herein described. 'llhe said heat generating conductor is provided with broad insulated terminals 5, preferably having perltorations 6 adapted to facilitate con.- nection to the electrical circuit. The armor may or may not extend over the back of the plate 1 but the edges should reach back suiiiciently to hold the armor securely in place and to supplement its adhesive hold.

in the construction shown in Fig. 3 a central mounting plate 8 is coated with suitable insulation 9 on both sides, the heat generating resistance conductor 1G is disposed about said plate and embedded in said insulating materialr in the torni of a progressive Winding whereby the generation of heatis distributed over the whole area et the plate, and an outer shell or'armor 11 is deposited upon the foregoing structure in the manner herein specified.

iF ig. d shows a section of armored Wire bent so as to show both a side view and -a transverse section, said wire comprising ak conductor core 15, a thin layer ot insulation 16 thereupon, andan outer casing or protective armor 17 consisting of any suitable refractory metal electro-deposited upon the insulation.

Fig. 5 shows a twisted pair of conductors or wires 18 embedded in and separated 'by insulating material 19 and an armor 20.

electro-deposited upon the insulation.

Figs. 6, 7, and f8' illustrate a special application of armoring on an electric beatin unit, showing an extension of the usefu ness ot such armor for the purpose of mechanically uniting the parts of the supporting :trame and the conductors. ln the forni shown, the trame 25 consists of radial arms 26 made of relatively thin and wide metal strips standing on edge and fastened at their center to a short metal tube or hub 27. rlhese arms are notched as at 28 upon their upper edge to adepth equal to the diameter of the heating wire 29 and its insulation. The thinly insulated heating conductor 29 is shown in the torni of a volute spiral, to each end of which is fastened a stud or terminal rod 30. Both studs have insulation continuous with that on the resistance conductor 29. The stud on the outer end of the spiral may be disposed against the side of the adjacenty arm '26 Where the armor will securely hold ir. '.l` he inner terminal stud may bei held in' place in the tube 27 by any suitable means as cement or packing 31. The top of the tube 27 is overlapping the uninsulated parts of the terminals, and thus short-circuitingor grounding the conductor on its armor.. `lit is intended that the insulated wire 29 should tightly lit the notches in the frame. 'llhe whole is now ready to be immersed in the Y electro-depositing bath and receive its metallic coating of integral armor 33.

llt is to be understood that/any suitable material may be used as a frame or support -for holding the heater elements constructed as shown in Figs. 1, 2, and 3 and in Figs.

6, 7, and 8. The armor may be made exible or rigid according to the quality of metal used and the thickness of the armor required, depending upon the purpose intended.

lt is further to be understood 'that wherever the'terms provided with, fastened to, or connected are used in the specili-l cation or claims in defining the relation or" the conductor to the terminals, these terms are to be construed in their broadest sense and are intended to cover all the usual and well known methods of forming such relations, as, for example, by having the conductor and terminal integral or by otherwise `joining them by any Well known metalworking or fastening means to eiiect the desired connection, as shown, tor instance, in Fig. 8.

Although several specific embodiments ot this invention are shown for clearness of the disclosure of the invention, no attempt has been made to show herein all of the forms and applications of the invention, and it will be understood that numerous details of the constructions shown may be altered or omitted without departing trom the spirit of this invention as defined by the following claims. o

l claim 1. A heating unit comprising a conductor,

insulating material substantially covering the same, and a closely adherent coating of refractory electrolytically deposited metal forming an armorfor said heating unit.

2. A heating unit comprising a conductor, insulating material substantially covering same, and a coating of electrolytically deposited nickel closely adherent to and substantially covering the surface of the insulating material.

3. A heating element comprising a conductor, terminals of higher conductivity connectedv to the conductor, insulationsubductor, terminals of higher con uctivity stantiallycovering theconductorand adjalstantially covering the conductor and adja-v cent portion of the terminals, and an armor of electrolytically deposited metal substantially covering the insulated portions of the conductor and terminals. 'i

4. A heating element comprising a conductor, -terminalsof higher conductivity connected to the conductor, insulation' substantially covering the conductor and 'adjacent portions of .theV terminals, and an armor of electrol tically depositedrefractory metal lsubstantie. 1y coverin the insulated portions v terminals. 5. A heating element comprisin of the conductor an a s conconnected to the conductor, insulationvsubconductor'and a part of the terminals, and

a layer of refractory insulation intervening between the conductor and,the metalfshell and extending beyond 'the shell surface of the terminals. l

1. An electric heater comprising a supporting skeleton frame, an insulated conductor arranged thereon -in the form of an portions ofthe upon they ber, 1913.

open grid, saidframe being notched t0 ref;

ceive said insulated conductor and said yframe and said insulated conductor both being covered by an integral closely adherent coating of refractory electrolytic metal.

8. An incandescent open 'lwork heater of spiral shape, in combination with ya light metal frame having armsarranged radially and adapted to support saidV conductor, and anv integral close fitting armor of refractory electrolytic metal incasingsaid frame and conductor and securing the same rigidly together. l 9. Al luminously radiant heat unit, comprising a frame including a' vertically disposed hub and a plurality of arms radiating therefrom vin a horizontal plane, a spiral conductor mounted on' said arms concentrically with said hub, thin refractory-1nsulating material covering said conductor,

said arms having .notches to receive the insulated conductor at the points of crossing, and a thin integral armor of electrolytic metal covering said conductor and said arms and joining the same rigidly together 1n a unitary manner..

Signed at Chicago this 4th day of Septem- -GHALRLES P. MADSEN.

Witnesses EUGENE A. RUMMLER, f

JENNIE BURT.

r4o unitary character, comprising an insulated' heat generating conductor of open volute 

